<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
      /*id选择器*/
        #p1{
          color: red;
        }
        /*类选择器*/
        .c1{
          color: aqua;
        }
        /*分组选择器*/
        h2,#p1,.c1{
          background-color: antiquewhite;
        }
        /*属性选择器*/
        input[type='text']{
          background-color: blue;
        }
        /*任意元素选择器*/
        *{
        /*边框: 粗细 实线边框 颜色*/
          border: 1px solid red;
        }
    </style>
</head>
<body>
<input type="text">
<input type="password">
<h2>老二</h2>
<p id="p1">苹果</p>
<p>香蕉</p>
<p class="c1">橘子</p>
<h3>电视</h3>
<h3 class="c1">冰箱</h3>
<h3>洗衣机</h3>
</body>
</html>